无法使用mysqli从数据库获取数据

I have got this code

$dafirstname = "SELECT fullname FROM websiteusers WHERE userName='$usernamer'";
$differentvariables = mysqli_query($link, $dafirstname);
$row = mysqli_fetch_array($differentvariables, MYSQLI_ASSOC);
printf("%s (%s)
", $row["pass"], $row["userID"]);

if(!mysqli_query($link,$dafirstname)){
  echo mysqli_error($link);     
}

But it does not print any thing or it is not giving any errors

Change your query. You were asking fullname only. change it to see the result.

$dafirstname="SELECT * FROM websiteusers WHERE userName='$usernamer'";
$differentvariables=mysqli_query($link,$dafirstname);
$row=mysqli_fetch_array($differentvariables,MYSQLI_ASSOC);
printf ("%s (%s)
", $row["pass"], $row["userID"]);
if(!mysqli_query($link,$dafirstname)){
  echo mysqli_error($link);     
}